This invention relates to thin metal-halogen cells capable of supplying stably high power for a long period of time and a process for producing the same.
With recent development of thinning in electronic equipment in civilian uses such as small-sized computers, electronic watches, and the like, a demand for thinned batteries as power sources has been increased. In batteries using electrolyte solutions such as silver oxide batteries, lithium batteries, etc., since it is necessary to completely seal the electrolyte solution in a metal container in order to prevent the battery from leakage, the construction becomes complicated, and precision instruments and severe production management are necessary for the production of these batteries, which results in making it difficult to thin these batteries. On the other hand, thinned batteries using solid electrolytes have simple construction without anxiety of leakage. According to conventional thin metal-halogen cells having solid eletrolytes, the cells have laminated construction produced by piling a relatively large amount of electrolyte powder on a metal plate, which is an anode active material, and laminating with pressure molding a mixture of a cathode active material of a halogen and a collector of carbonaceous powder thereon. But these thin cells had many defects in that it was difficult to make the cells about 2 mm or less in thickness; there were limitations in form, such as in shape, size, and the like; and the active materials of both electrodes were easily exhausted by self-discharge in many cases, which resulted in shortening of shelf life of the cells.
In order to overcome these defects as mentioned above, the present inventors have studied eagerly on thin or ultra-thin cells and a process for producing the same and found that such thin or ultra-thin galvanic cells with novel form having a combination of an electrochemically active metal and a halogen can be produced by using technics of forming thin films of a metal as anode active material and a solid electrolyte and of laminating a cathode active material and an electroconductive plastic film thereon by using an adhesive, that is, thin or ultra-thin cells can easily be produced by a step of forming thin films such as vacuum evaporation coating or sputtering and a step of laminating by using an adhesive, and accomplished the present invention.